MIMO Transmission schemes for LTE and HSPA Networks, 3G

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1 TERMINOLOGYIt is assumed that the reader is familiar with common 3GPP standards terms described in [3]. Terminology thatis outside of the scope of [3] is provided below.Antenna EfficiencyBPDCDDCLACL-MIMOCoMPCorrelation (p)CSICQIDFTDIVEMCFDDHACMMSEMU-MIMOOFDMOL-MIMORMaRRHSARSDMASFBCSINRSMSU-MIMOTDDTTITXDULAUMaUMiRatio of radiated power from/to antenna vs. conducted power to/from antenna.Branch Power Difference - The difference in the efficiencies between the main anddiversity (secondary) antenna.Cyclic Delay DiversityFamily of clustered linear antenna configurations such as those resulting fromforming clusters of closely spaced antenna elements while separating these clusterseither by widely spacing them or by different polarizations.Closed Loop MIMOCoordinated Multipoint Transmission/ReceptionCross correlation of received signal power/phase for antennas over space or atraveled route. Generally, as the correlation value increases, the ability of thediversity antenna system to provide any gains decreases. For the SM case, targetenvelope correlation should be between 0.5 (worst case) and 0.3 (goodperformance). For simple diversity implementations, target envelope correlationshould be < 0.7.Channel State InformationChannel Quality IndicationDiscrete Fourier TransformFamily of diversity antenna configurations such as those resulting from all elementsbeing widely spaced or separated by different polarizationsElectromagnetic CompatibilityFrequency Division DuplexHearing Aid CompatibilityMinimum Mean Square ErrorMultiuser MIMOOrthogonal Frequency Division MultiplexingOpen Loop MIMORural Macrocell deployment typeRemote Radio HeadSpecific Absorption RateSpace Division Multiple AccessSpace Frequency Block CodingSignal to Interference and Noise RatioSpatial MultiplexingSingle User MIMOTime Division DuplexTransmission Time IntervalTransmit DiversityFamily of uniform linear array antenna configurations such as those resulting fromall elements being uniformly closely spaced.Urban Macrocell deployment typeUrban Microcell deployment type4
2 EXECUTIVE SUMMARYFor over a decade universities and wireless research labs have been combining multiple antennatransmission techniques with advanced signal processing algorithms to create what is sometimes calledsmart-antenna and is also known as multi-input multi-output (MIMO) technology. These schemes are nowmoving into mainstream communication systems. Indeed, MIMO technologies can already be found inwireless local area network access points (e.g. 802.11n based solutions). This has led to MIMO beingstandardized in WiMAX as well as in 3GPP Rel-6 and Rel-7 of the UTRAN (HSPA) specifications. Further,Rel-8 of the E-UTRAN (LTE) 3GPP specifications, completed in March 2009, included the most advancedforms of MIMO in any standard in the industry. And even more advanced MIMO enhancements are currentlybeing studied for inclusion in 3GPP Rel-9 and Rel-10.There are many MIMO schemes standardized in 3GPP systems, and the base station scheduler has thecapability to optimally select the MIMO scheme that suits the channel conditions of the mobile. A fundamentalMIMO scheme is that of precoded spatial multiplexing (SM) where multiple information “streams” aretransmitted simultaneously from the base station to the mobile. These techniques are appropriate in highSINR areas with rich scattering environments, in combination with suitable antenna configurations.Measurements at the base station receiver and feedback signals by the mobile help the base stationdetermine the number of information streams that can be supported across single or multiple users. SM isaugmented with techniques such as beamforming and open loop transmit diversity that can be used as thechannel conditions become less favorable to spatial multiplexing. The ability to dynamically adapt to thechannel optimal MIMO scheme as channel conditions change is a key focus of the LTE Rel-8 specifications.Antenna configurations at the tower have an impact on the types of MIMO schemes that are available to thebase station. Narrowly spaced antennas are ideal for supporting beamforming, while widely spaced or crosspole antennas are ideal for spatial multiplexing and transmit diversity. The choice of antenna at the basestation will depend on several factors including the expected performance benefits for the particulardeployment environment as well as real estate and cost considerations at the tower. At the terminal, thedevice form factor as well as operation at lower frequency bands further challenges designers in terms ofachieving the required antenna efficiencies. Performance benefits of various MIMO schemes are shownthrough system simulation results, and demonstrate that both peak throughput as well as system and edgespectral efficiency are increased with MIMO techniques. In the paper, a technology-oriented approach wasfollowed, leaving many real-world deployment and MIMO BS antenna design issues untreated. These includeissues ranging from antenna sharing at the tower, to antenna beam design, to wind loading and many othersworth of a separate white paper dedicated to this subject.This paper is organized as follows. In Section 3, we provide the principles behind smart antenna technologiessuch that the reader will be able to understand the fundamental tradeoffs. We then describe many antennaconfigurations that can support a wide range of MIMO algorithms at the base station as well as extensivelytreat the issues behind the antenna configurations at the terminal. Section 4, addresses the specific schemesselected by 3GPP to provide smart antenna capabilities in HSPA and LTE Rel-8. Section 5 focuses on theexpected standardization outcome in Rel-9 and Rel-10 and more specifically, in enhancements behindclustered linear arrays (CLA) and collaborative multipoint transmission/reception (CoMP) schemes. Section 6provides performance results for a wide variety of channel conditions, and antenna configurations for both DLand UL. Closing, Section 7, provides some concluding remarks effectively distilling the performance results ofsection 6 down to few guiding trends and recommendations.The 3GPP specifications have already defined and continue to define the most advanced forms of MIMOtechnology in the industry. We certainly hope that this report increases awareness and helps guide thedeployment of MIMO technology in HSPA and LTE networks.5
Page 2 and 3: Table of Contents1 TERMINOLOGY ....
Page 6 and 7: 3 PRINCIPLES3.1 MULTI‐ANTENNA‐T
Page 8 and 9: 3.1.3 PEAK RATE OR COVERAGEIn a cel
Page 10 and 11: sufficiently accurate channel infor
Page 12 and 13: Figure 5. Examples of Power Delay P
Page 14 and 15: 3.2 BS ANTENNA CONFIGURATIONSFigure
Page 16 and 17: NOTE:Implementation complexity refe
Page 18 and 19: 3.3.4 ADVANCED‐ANTENNA CONCEPTS F
Page 20 and 21: and interference. By considering th
Page 22 and 23: ank over all the feasible 1 set of
Page 24 and 25: Typically a constant delay increase
Page 26 and 27: the columns of Λ U r rxrfor some o
Page 28 and 29: to blindly estimate this power rati
Page 30 and 31: Figure 16. MMSE Receiver for UL MU-
Page 32: transmitter has information about t
Page 35 and 36: Intra-site CoMPBS3BS2Inter-site CoM
Page 37 and 38: 5.5.4 UL COMPUplink coordinated mul
Page 39 and 40: 6.2 DL SYSTEM PERFORMANCE6.2.1 THE
Page 41 and 42: Compared to baseline, SE gains for
Page 43 and 44: 6.2.3. CL‐MIMO WITH DIV ANTENNA C
Page 45 and 46: 6.2.4. MIMO WITH ULA‐4VWith the U
Page 47 and 48: 0.035Baseline Uplink Cell Edge Sect
Page 49 and 50: 7 CONCLUDING REMARKSThis report pro

MIMO Transmission schemes for LTE and HSPA Networks, 3G

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